Optional Partials in DustJS - node.js

Question

Is it possible to have optional partials in Dust? Let's say I define a layout like this:
<div>
{>"{module}"/>
</div>
I have been defining the module in Express's res.locals object. However, what if I forgot to define a module, or I actually want a default module for use when I do not define one? Worse, what if I did define one but it's the incorrect module, meaning there's no template file in the view folder with the name of that module? I don't want the user to see the ugly error message, which seems to be something like:
Error: ENOENT, open 'view_path\{module}.dust'
where {module} is the name of the module, or an empty string if I did not specify a res.locals.module. Should I resort to try-catch blocks (not even sure how to do them in dust), or is there a method for making templates optional, rather than required? NOTE: The template would be optional, but the module variable would (usually) still be a string. It seems that dust sections are optional, meaning if the exact key is not available, the section is simply not included. For example, say I have the context {friends: [{name: "Harry"}, {name: "Ron"}, {name: "Hermione"}]}. If I define the section:
{#friends}
{name} is {age} years old.
{/friends}
it will output
Harry is years old.
Ron is years old.
Hermione is years old.
Notice there are 2 spaces between is and years in each case, where the age would be if we defined any ages. If this functionality is included, how is it that neither the original creators of dust nor LinkedIn thought to not require partials? How do I specify optional partials in dust?

Answer 1

You could use a conditional like so,
<div>
{?module}
{>"{module}"/>
{:else}
{>"{YourDefaultPartial}"}
{/module}
</div>
This will work when {module} is either undefined or an empty string or a falsey value.
But, in case its a string pointing to a partial that does not exist, it'll throw an error. Hope this helps.